The invention relates to a process and an installation for the production of foam in a continuous slabstock foam process, in particular the production of polyurethane foam.
The product quality of foams depends on a large number of environmental parameters and installation parameters. This applies in particular to the production of polyurethane foam. A mathematical model for the production of polyurethane foam which involves some of these parameters is known from Shell Petrochemicals, No. 5, 1987, page 14, “An Expert Touch for PU Foam Production”, Philip Connolly.
Various parameters which are of importance for the production of polyurethane foam are known from Journal of CELLULAR PLASTICS, January/February 1983, “Flexible Polyurethane Slabstock Foam: The Influence of Formulation, Climatic Conditions and Storage Conditions on Foam Properties”, Dr. R. Schiffauer and C. den Heijer. In particular, the marked dependence of the production process on environmental conditions, such as, for example, on the atmospheric pressure and the atmospheric humidity, can lead to a summer-winter effect in the production.
For quality assurance in the production of polyurethane foam it is known to analyze the properties of the starting substances and also to subject the end product to a comprehensive analysis. It is known from “Qualitätssicherung von PUR-Schaumstoffen, Prüfung des Steigverhaltens mit Ultraschall”, B. Hofmann and J. Albertz, Kunststoffe 86 (1996) to determine the rising properties of the mixed starting substances by means of ultrasonic sensors. A similar process for quality control is known from “Ultrasonics for foam measurements: a quality control tool for PU foams”, Dr. Ing. Dirk Wehrhahn, Urethanes Technology, August/September 1991. The pulse-echo method is used for the ultrasonic measurement.
Another measurement system for foam heights based on an ultrasonic measurement of distance is known from “Qualität gibt den Takt an”, Kunststoffberater (1993), 38 (6), page 11. An alternative sensor principle based on a CCD camera is known from “Use of a charged coupled device (CCD) camera for evanescent wave optical fiber cure monitoring of liquid composite molding resins”, Polym. Compos. (1977) 18 (4), pages 518–525. A sensor for measurement of the expansion of foam which determines the weight and the thickness of the foam is known from JP 103 29 160.
A process for the characterization of the foam produced is known from “Non-destructive characterization of microcellular foam structure. Error analysis of a proposed sensor”, Annu. Tech. Conf. Soc. Plast. Eng. (1992), pages 1519–1526.
Various computer-assisted methods of quality assurance in the production of polyurethane foam have also been disclosed in, for example, from “Software to Manage a Continuous Production of Flexible Polyurethane Foams by Slabstock Technology”, Salvatore Consoli, Journal of CELLULAR PLASTICS, volume 33, March 1997, page 102; “Foam Roadmap On-Line Answernostics”, James D. Shoup, Polyurethane 1995, Sep. 26th–29th, 1995, pages 489, 490; and “Mathematical Property Prediction Models for Flexible Polyurethane Foams”, Reinhart Schiffauer, Adv. Urethane Sci. Techn. 14 (1998), pages 1 to 44.
Expert systems for processing parameters during RIM processing are known from “Experten mit System, Prozesssteuerung des PUR-RRIM-Verfahrens zur Herstellung von Karosserieauβenteilen”, F. Schnabel, Sulzbach, K. -H. Dörner, Kunststoffe, year 88, October,98; and “PUR-Teile kostengünstig fertigen, Stand der Polyurethan-RRIM-Technologie”, Karl-Heinz Dörner, Hans Joachim Meiners, Hans-Joachim Ludwig, Kunststoffe, year 91, April,2001. These expert systems are said to be able to provide conclusions in respect of the product properties, process monitoring, quality assurance and preventive maintenance.
Various types of installations for the production of polyurethane slabstock foam and other foams are known from the prior art. Such installations are obtainable commercially from Hennecke GmbH, Birlinghovener Straβe 30, 53754 Sankt Augustin, Germany, particularly installations for the production of slabstock flexible foam in continuous production. Such installations are also called slabstock foam installations.
Other types of slabstock foam installations known from the prior art include those disclosed in Planiblock, Draka-Petzetakis, Maxfoam and Vertifoam Edge Control (Kunststoffhandbuch; 7. Polyurethane; ed. Oertel, G.; Munich; Vienna; Hanser Verlag, 1993) and those suitable for the VPF (variable pressure foaming) process. Polyurethane flexible foam is also produced in a continuous rectangular process in these types of installations.
Various types of installations for the production of polyurethane in a continuous slabstock foam process are commercially obtainable from Cannon Viking, Manchester, England.
Various devices for the continuous production of polyurethane foam blocks are disclosed in DE 691 19 244 T2; DE 692 17 671 T2; and U.S. Pat. No. 4,492,664. Another apparatus for the production of polyurethane foam is known from DE 696 10 885 T2.
Various processes for the production of polyurethane foams on such installations are described, for example, in DE 381 99 40 A1; DE 196, 49, 829 A1; DE 431 5874 A1; and DE 195 06 671 C2.